1. Field of the Invention
The invention relates to a vibration exciter and to an oscillating motor for use in a vibration exciter.
2. The Prior Art
In construction, vibration generators such as vibrators, shakers, or vibratory pile drivers are used to introduce or draw profiles into the ground, or also to compact soil material. The ground is excited by means of vibration, and thereby achieves a “pseudo-fluid” state. The goods to be driven in can then be pressed into the construction ground by means of a static top load. The vibration is characterized by a linear movement and is generated by means of rotating imbalances that run in opposite directions, in pairs, within a vibrator gear mechanism. Vibration generators are characterized by the imbalance that is installed (referred to as “static moment” in technical circles) and by the maximal speed of rotation.
In order to achieve an optimal advance and good compacting, as a function of the goods to be driven in and of the soil properties, it is desirable to regulate the amplitude, frequency, or force direction of the vibration generator. It is practical if the adjustment of the vibration takes place by way of a change in the static moment or the phase position of the imbalances. When the vibration exciter is started up, the inherent frequency range of the soil is passed through. If the soil is excited in the resonance range, the amplitude of the soil vibration becomes very great, and this can result in damage to adjacent buildings. Therefore, no imbalances can be in effect when the vibration exciter is started up.
Known solutions such as planetary gear mechanisms or oscillating gear trains require a lot of space, are not well suited for high speeds of rotation, and produce a high noise level because of additional gear wheels.
To solve this problem, it was proposed in German Patent No. DE 41 18 069 A1 to use a rotary piston adjustment device for orienting imbalance masses. It was shown, however, that with such devices, such as a rotor oscillating motor, leakages occur after only a short period of time at the required high hydraulic pressures that must be guaranteed over a long period of time. This makes complicated control and regulation devices necessary, in order to keep the relative position of the imbalance masses constant.